Guard for when refreshing token fails

[balloob]

Breaking change

Proposed change

When starting up Spotify I got 503 error and the integration was unable to recover. Fixed this by wrapping the refresh token logic at startup and handle errors.

Traceback (most recent call last):
  File "/home/paulus/dev/hass/core/homeassistant/config_entries.py", line 236, in async_setup
    result = await component.async_setup_entry(hass, self)  # type: ignore
  File "/home/paulus/dev/hass/core/homeassistant/components/spotify/__init__.py", line 65, in async_setup_entry
    await session.async_ensure_token_valid()
  File "/home/paulus/dev/hass/core/homeassistant/helpers/config_entry_oauth2_flow.py", line 465, in async_ensure_token_valid
    new_token = await self.implementation.async_refresh_token(self.token)
  File "/home/paulus/dev/hass/core/homeassistant/helpers/config_entry_oauth2_flow.py", line 84, in async_refresh_token
    new_token = await self._async_refresh_token(token)
  File "/home/paulus/dev/hass/core/homeassistant/helpers/config_entry_oauth2_flow.py", line 175, in _async_refresh_token
    new_token = await self._token_request(
  File "/home/paulus/dev/hass/core/homeassistant/helpers/config_entry_oauth2_flow.py", line 194, in _token_request
    resp.raise_for_status()
  File "/home/paulus/dev/hass/core/venv/lib/python3.8/site-packages/aiohttp/client_reqrep.py", line 1002, in raise_for_status
    raise ClientResponseError(
aiohttp.client_exceptions.ClientResponseError: 503, message='Service Unavailable', url=URL('https://accounts.spotify.com/api/token')

Type of change

• Dependency upgrade
• Bugfix (non-breaking change which fixes an issue)
• New integration (thank you!)
• New feature (which adds functionality to an existing integration)
• Breaking change (fix/feature causing existing functionality to break)
• Code quality improvements to existing code or addition of tests

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# Example configuration.yaml

Additional information

• This PR fixes or closes issue: fixes #
• This PR is related to issue:
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• The code change is tested and works locally.
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[probot-home-assistant]

Hey there @frenck, mind taking a look at this pull request as its been labeled with an integration (spotify) you are listed as a codeowner for? Thanks!
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